AJAX+Servlet实现的数据处理显示功能示例

来源：爱玩科技网

本文实例讲述了AJAX+Servlet实现的数据处理显示功能。分享给大家供大家参考，具体如下：

实现功能：在输入框中输入字符，用AJAX传到后台Servlet处理后加上随机数，并返回到前台显示。

一、写前台jsp页面index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
 <title>My JSP 'index.jsp' starting page</title>
 <script type="text/javascript">
 /*
 ajax 的几个步骤：
 1、建立XmlHttpRequest对象
 2、设置回调函数
 3、使用Open方法建立与服务器的连接
 4、向服务器发送数据
 5、在回调函数中针对不同响应状态进行处理
 */
 var xmlHttp;
 function createXMLHttpRequest(){ //1建立XmlHttpRequest对象
 if(window.ActiveXObject){
 try{
 xmlHttp = new ActiveXObject("Microsoft.XMLHttp");
 }catch(e){
 alert("Error!!!");
 }
 }else{
 xmlHttp = new XMLHttpRequest();
 }
 }
 function showMes(){ //2设置回调函数
 if(xmlHttp.readyState==4){ //数据接收完成并可以使用
 if(xmlHttp.status==200){ //http状态OK
 //5、在回调函数中针对不同响应状态进行处理
 document.getElementById("sp").innerHTML = xmlHttp.responseText; //服务器的响应内容
 }else{
 alert("出错："+xmlHttp.statusText); //HTTP状态码对应的文本
 }
 }
 }
 /**
 //这是GET方法传送
 function getMes(){
 createXMLHttpRequest();
 var txt = document.getElementById("txt").value;
 var url="servlet/AjaxServlet?txt="+txt;
 url = encodeURI(url); //转换码后再传输
 xmlHttp.open("GET",url,true); //3使用Open方法建立与服务器的连接
 xmlHttp.onreadystatechange=showMes;
 xmlHttp.send(null); //4向服务器发送数据
 }
 */
 /**
 *这是post方法
 */
 function postMes(){
 createXMLHttpRequest();
 var txt = document.getElementById("txt").value;
 var url = "servlet/AjaxServlet";
 var params = "username="+txt;
 // alert(params);
 xmlHttp.open("POST",url,true);
 xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=UTF-8");
 xmlHttp.send(params);
 xmlHttp.onreadystatechange = showMes;
 }
 </script>
 </head>
 <body>
 <input type="text" id="txt"/>
 <input type="button" value="query" onclick="postMes()" />
 <span id="sp"></span>
 </body>
</html>

二、写后台Servlet加random随机数，关键代码如下：

public void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 request.setCharacterEncoding("utf-8"); //用utf-8转换获得传输过来的码
 response.setContentType("text/html");
 PrintWriter out = response.getWriter();
 String txt = request.getParameter("txt");
// String tx = new String(txt.getBytes("iso-8859"),"utf-8");
 out.print("txt="+txt+Math.random());
 out.flush();
 out.close();
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 request.setCharacterEncoding("utf-8");
 response.setContentType("text/html;charset=UTF-8");
 PrintWriter out = response.getWriter();
 String username = request.getParameter("username");
// String txt = new String(username.getBytes("ISO-8859-1"),"UTF-8");
 String txt = new String(username);
 out.print("txt="+txt+":"+Math.random());
 out.flush();
 out.close();
}

更多关于ajax相关内容感兴趣的读者可查看本站专题：《jquery中Ajax用法总结》、《JavaScript中ajax操作技巧总结》、《PHP+ajax技巧与应用小结》及《asp.net ajax技巧总结专题》

希望本文所述对大家ajax程序设计有所帮助。